Marked attenuation of the amplitude of transcranial motor-evoked potentials after intravenous bolus administration of ketamine: a case report

• Published in: Journal of medical case reports 2018-07, Vol.12 (1), p.204-204, Article 204
• Main Authors: Furutani, Kenta, Matsuhashi, Mari, Deguchi, Hiroyuki, Mitsuma, Yusuke, Ohashi, Nobuko, Baba, Hiroshi
• Format: Article
• Language: English
• Subjects: Administration, Intravenous; Adolescent; Anesthesia; Anesthesiology; Anesthetics, Dissociative - administration & dosage; Anesthetics, Dissociative - pharmacology; Bolus administration; Case Report; Case reports; Drug dosages; Drug therapy; Evoked potentials; Evoked Potentials, Motor - drug effects; Female; Health aspects; Humans; Intraoperative Neurophysiological Monitoring; Ketamine; Ketamine - administration & dosage; Ketamine - pharmacology; Monitoring; Motor-evoked potentials; Pain; Patient outcomes; Proteins; Scoliosis; Scoliosis - surgery; Spinal Fusion; Spine surgery; Surgery; Systematic review
• ISSN: 1752-1947; 1752-1947
• DOI: 10.1186/s13256-018-1741-9

It is believed that ketamine does not affect motor-evoked potential amplitude, whereas various anesthetic drugs attenuate the amplitude of transcranial motor-evoked potential. However, we encountered a patient with marked attenuation of motor-evoked potential amplitude after intravenous bolus administration of ketamine. A 15-year-old Japanese girl with a diagnosis of adolescent idiopathic scoliosis was admitted to our hospital to undergo posterior spinal fusion at T4-L3. After induction of general anesthesia using a continuous infusion of propofol and remifentanil, we confirmed that transcranial electrical motor-evoked potentials were being recorded correctly. Ketamine 1.25 mg/kg was administered intravenously for intraoperative and postoperative analgesia. About 3 minutes later, the motor-evoked potential amplitude was markedly attenuated. No other drugs were administered except for ketamine. The patient's vital signs were stable, and the surgery had not yet started. The motor-evoked potential amplitude was recovered at about 6 minutes after administration of ketamine. The surgery was performed uneventfully, and the patient had no neurologic deficit when she emerged from general anesthesia. Although there is a widely held belief in the field of anesthesiology that ketamine does not affect motor-evoked potential amplitude, it has been suggested that ketamine could affect its monitoring.